usb: misc: ks_bridge: Clean the driver

Clean/refactor the driver. Specifically, make following changes:
 - Remove support for Interrupt IN data endpoint
 - Append ZLP after every OUT URB
 - Add/Fix debug and error prints
 - Other miscellaneous cleanup and refactoring.

Change-Id: I08dab6018b47cc9c3b559b054f1742624c46a816
Signed-off-by: Ajay Agarwal <ajaya@codeaurora.org>